A case-control study of newly diagnosed lymphomas, excluding Hodgkin's disease, in the practice of selected physicians associated with hospitals of the Harvard Medical School, Tufts University Medical Center, and Boston University School of Medicine will be carried out. Newly diagnosed cases in the years 1984 to 1986 will be identified through two mechanisms, an ongoing reporting system for cancer for a number of Harvard hospitals and a special reporting system developed for a precursor study of cases diagnosed in 1980 to 1982. It is anticipated that somewhat more than 350 cases with these diagnoses will be seen in these years and that approximately 300 will satisfy eligibility requirements of histologic confirmation, date of diagnosis in the specified years, and residence in eastern Massachusetts, and will agree to cooperation in the study. One matched control subject will be chosen for each case, matched as to age, sex, and neighborhood of residence, and selected through Massachusetts Town Books of residents of the state, listed by street address. Home interviews of cases and controls will be done by trained interviewers, directed at eleven areas of study with special interest in associations with common allergies, vaccinations, and drugs used for treatment of allergies and other disturbances of immune system. These exposures have been implicated in lymphomas in a study of new cases in 1980 to 1982 in this geographic area.